VL30 retro-transposons are TRIM24-repressed enhancers that generate non-coding RNA to regulate gene expression in mouse hepatocytes. [RNA-Seq]

TRIM24 and TRIM33 interact to form a corepressor complex that suppresses murine hepatocellular carcinoma (HCC). TRIM24 and TRIM33 cooperatively repress retinoic acid receptor dependent activity of VL30 retro-transposons in hepatocytes in vivo. In TRIM24 knockout hepatocytes, VL30 long terminal repeats (LTRs) generate enhancer (e)RNAs and act as surrogate promoter and enhancer elements deregulating expression of neighbouring genes. We show that a VL30 LTR-derived eRNA is essential to activate the lipocalin 13 gene in hepatocytes in vivo. A further consequence of VL30 de-repression is the accumulation of retro-transcribed VL30 DNA in the cytoplasm of TRIM24-mutant hepatocytes and activation of the viral defence/interferon response. VL30 activation therefore modulates gene expression via the enhancer activity of the LTRs and by activation of the interferon response. Both of these processes are genetically linked to HCC development suggesting that VL30 repression by TRIM24 plays an important role in tumour suppression. Overall design: RNA profiles in liver of wild type (WT) and Trim24-/- mice by deep sequencing using Illumina GAIIx.

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Herquel B, Ouararhni K, Martianov I, Le Gras S, Ye T, Keime C, Lerouge T, Jost B, Cammas F, Losson R, Davidson I